The present invention relates to apparatus for pressurizing a fluid or liquid such as water, specifically, to a powered system for delivering a fluid or liquid from a supply source and discharging it at a greater pressure, and particularly, to a pressure washer.
Prior to the present invention, pressure washers generally included an induction motor which is continually energized during the entire operation of the pressure washer. Prior pressure washers further included an unloader valve which recirculates water under high pressure in the pump. Delivery of water was controlled by a valve in the water delivery line. Therefore, when the delivery valve was closed, the line pressure would increase opening the unloader valve which would recirculate the water around the pump.
Several disadvantages of prior pressure washers can then be immediately recognized. First, the induction motor, the unloader valve, the delivery valve, and parts required in association therewith are costly. Thus, the major market for prior pressure washers has been for commercial applications as the cost versus benefits has been too large for most consumer applications. Further, oil sump lubrication is utilized in prior pressure washers and which increases the complexity, weight and cost of prior pressure washers.
Additionally, the induction motor is extremely heavy and with the combined weight of the total components limiting portability and making prior washers difficult to transport and utilize. Thus, prior pressure washers have been directed towards commercial applications.
The use of unloader valves is also disadvantageous. Specifically, the recirculated water in the unloader valve becomes very hot especially when the pressure washer is operated for a long period of time without the delivery of water. This heat generation is detrimental to the operation and life of the seals of the pump and of the motor. Further, even when the pressure washer is delivering water, the unloader valve recirculates a small amount of water around the pump to avoid generation of high pressure peaks when the unloader valves unloads. This continual recirculation of water reduces the delivery pressure of the water and results in inefficiencies.
Thus, a need has arisen for innovations allowing the reduction of cost and weight of pressure washers to make such pressure washers particularly adapted for the consumer market.